[shrx]

I'm curious about what kind of visualization does the ATC have at the disposal about the current occupancy of the individual tarmac segments? I'd assume if an airplane is approaching for landing on a specific runway, that runway should have been clearly marked as restricted for access until the plane would actually land and clear it?

[cjrp]

In the US, airplanes can be cleared for landing while the runway is occupied (you can be number two, three, etc. for landing and still be cleared). It's different in other countries, where you can only be issued a landing clearance if the runway is clear or anticipated to be clear before you land (e.g. the plane before you is already exiting the runway).

[shrx]

Still, the runway could be reserved for landing aircrafts only, still preventing access to all other types of vehicles.

[danso]

How are fire trucks supposed to respond to incidents involving airplanes, as it appears this case involves, if the runway is off limits to them?

[nradov]

The way it's supposed to work, the ground controller first verifies that there are no traffic conflicts before clearing vehicles to cross an active runway.

[bombcar]

Which is exactly what failed here, so saying "it shouldn't fail by not failing" doesn't help terribly much.

Having grade-separate crossings for vehicles might, but that introduces new issues (plane skidding off runway could hit the incline and break up).

[selectodude]

O’Hare has those but it’s not helpful for emergencies that happen on the runway itself.

[shrx]

That is exactly my point. What visual aids do the ATC controllers have at their disposal to decide if the runway is free for an emergency vehicle to pass?

[shrx]

If it's not safe to use, then they should wait or go around. Otherwise accidents like this one happen.